Abstract

Background

Electronic cigarettes (e-cigarettes) are generally recognized as a safer alternative
to combusted tobacco products, but there are conflicting claims about the degree to
which these products warrant concern for the health of the vapers (e-cigarette users).
This paper reviews available data on chemistry of aerosols and liquids of electronic
cigarettes and compares modeled exposure of vapers with occupational safety standards.

Methods

Both peer-reviewed and “grey” literature were accessed and more than 9,000 observations
of highly variable quality were extracted. Comparisons to the most universally recognized
workplace exposure standards, Threshold Limit Values (TLVs), were conducted under
“worst case” assumptions about both chemical content of aerosol and liquids as well
as behavior of vapers.

Results

There was no evidence of potential for exposures of e-cigarette users to contaminants
that are associated with risk to health at a level that would warrant attention if
it were an involuntary workplace exposures. The vast majority of predicted exposures
are < <1% of TLV. Predicted exposures to acrolein and formaldehyde are typically <5%
TLV. Considering exposure to the aerosol as a mixture of contaminants did not indicate
that exceeding half of TLV for mixtures was plausible. Only exposures to the declared
major ingredients -- propylene glycol and glycerin -- warrant attention because of
precautionary nature of TLVs for exposures to hydrocarbons with no established toxicity.

Conclusions

Current state of knowledge about chemistry of liquids and aerosols associated with
electronic cigarettes indicates that there is no evidence that vaping produces inhalable
exposures to contaminants of the aerosol that would warrant health concerns by the standards that are used
to ensure safety of workplaces. However, the aerosol generated during vaping as a
whole (contaminants plus declared ingredients) creates personal exposures that would justify surveillance of health among exposed
persons in conjunction with investigation of means to keep any adverse health effects
as low as reasonably achievable. Exposures of bystanders are likely to be orders of
magnitude less, and thus pose no apparent concern.